[Typo3] Help! can't call FE and BE! sv and cms not loaded suddenly

[Steffen Matzke]

hello,

suddenly, i can't call my website, neither the frontend nor the backend.

when i try to open the frontend i get the following error msg:
Error: The main frontend extension "cms" was not loaded. Enable it in 
the extension manager in the backend.

and this, when i want to go to my BE:
TYPO3 Fatal Error: Extension key "sv" was NOT loaded! 
(t3lib_extMgm::extPath)


what happend? i've merely edited some pages with templavoila.

i use typo3 3.8.

could somebody help, please?

steffen